The present invention relates to a surgical cross-connecting apparatus and a cross-connecting surgical screw apparatus for use with implantation rods, and related methods of securing implantation rods using a surgical cross-connecting apparatus.
The bones and connective tissue of an adult human spinal column consists of more than 20 discrete bones coupled sequentially to one another by a tri-joint complex. The complex consists of an anterior disc and two posterior facet joints. The anterior discs of adjacent bones are cushioned by cartilage spacers referred to as intervertebral discs. The over 20 bones of the spinal column are anatomically categorized as one of four classification: cervical, thoracic, lumbar, or sacral. The cervical portion of the spine which comprises the top of the spine up to the base of the skull, includes the first 7 vertebrae. The intermediate 12 bones are thoracic vertebrae, and connect to the lower spine comprising the 5 lumbar vertebrae. The base of the spine is a sacral bones (including the coccyx).
The spinal column of bones is high complex in that it includes the over 20 bones coupled to one another, housing and protecting critical elements of the nervous system having innumerable peripheral nerves and circulatory bodies in close proximity. Despite its complexity, the spine is a highly flexible structure, capable of a high degree of curvature and twist in nearly every direction.
Genetic or developmental irregularities, trauma, chronic stress, tumors and disease, however, can result in spinal pathologies which either limit this range of motion, or which threatens the critical elements of the nervous system housed within the spinal column. A variety of systems have been disclosed in the art which achieve this immobilization by implanting artificial assemblies in or on the spinal column. These assemblies may be classified as anterior posterior or lateral implants. Lateral and anterior assemblies are coupled to the anterior portion of the spine which is in the sequence of vertebral bodies. Posterior implants generally comprise pairs of rods, which are aligned along the axis which the bones are to be disposed, and which are then attached to the spinal column by either hooks which couple to the lamina or attach to the transverse processes, or by screws which are inserted through the pedicles. In order to provide enhanced torsional rigidity, these implants generally include cross-connecting devices which couple the rods together transverse to the axis of the implants. These cross-connecting devices may couple directly to the rods themselves, or may be attached to the pedicle screws.
Exemplary prior art references include U.S. Pat. Nos. 5,005,562, 5,334,203, 5,688,272, 5,716,355, and 5,947,966.
It is desirable to provide cross-connecting devices that are adjustable and can form angular installments by taking advantage of various degrees of freedom possessed by components of the device.
The present invention is directed to surgical cross-connecting apparatuses in which the components of the apparatuses are adjustable as a result of being provided with a number of degrees of freedom. For instance, the components are movable axially and rotatably. The components are rotatable in several different ways taken from the perspective of the axially extending cross connecting member of the apparatuses.
In one embodiment, the surgical cross-connecting apparatus comprises a cross connecting member extending in an axial direction having at least one end provided with a hook that is mounted in an opening in the end, wherein the hook has an opening sized to receive a spinal rod, the hook being rotatable in the plane in which the cross connecting member extends, and a screw member fitted into an aperture which engages the spinal rod and locks the rod within the hook. In another embodiment, this hook is also provided at a second end of the cross connecting member.
In yet a further embodiment, the opening in the first end is a slot in which the hook is moveable in the axial direction in which the cross connecting member extends. In yet another embodiment, the cross connecting member is provided with a second end having a hook that is mounted in an opening in the second end, the opening of the second end being a slot in which the hook is moveable within the axial direction in which the cross connecting member extends.
Yet another embodiment is a surgical cross-connecting apparatus comprising at least one body positioned at an end of a cross connecting member extending in an axial direction, the body being provided with a cavity for receiving a spinal rod, a lever pivotally mounted to the body, a set screw mounted in a through hole in the lever that is positioned proximate to the cross connecting member so that the set screw bears against the cross connecting member when the set screw is tightened, wherein at least a portion of the lever defines a portion of the cavity. The body is rotatably mounted over the cross connecting member to rotate around the axial direction in which the cross connecting member extends. In yet another embodiment, in addition to having the body at a first end of the cross connecting member, a second end of the cross connecting member has an aperture, wherein the aperture is sized to receive an end of a hook, the end of the hook defining a second aperture in which means for fixing in place a spinal rod placed within the hook, wherein the hook is rotatable around the axis formed by the cross connecting member. In yet another embodiment, the bodies are located at both ends of the cross connecting member.
Still another embodiment is a surgical cross-connecting apparatus, comprising at least one body positioned at an end of a cross connecting member that extends in an axial direction, the end having a thickness that is less than the thickness of a central portion of the cross connecting member, the end being provided with a pin extending into a slot provided on the body, the body being provided with a cavity for receiving a spinal rod, a lever pivotally mounted to the body, a set screw mounted in a through hole in the lever that is positioned proximate to the cross connecting member so that the set screw bears against the cross connecting member when the set screw is tightened, wherein at least a portion of the lever defines a portion of the cavity. The pin is located on an underside of the cross connecting member and the slot is located on an underside of the body. The structure of this embodiment allows the body to rotate in the plane in which the cross connecting member extends. Also, the body is movable in the axial direction in which the cross connecting member extends. Other embodiments incorporate this body at a second end of the cross connecting member, or any of the other bodies previously described.
Yet another embodiment is a surgical cross-connecting apparatus comprising at least one body positioned at an end of a cross connecting member extending in an axial direction, the end having a thickness that is less than the thickness of a central portion of the cross connecting member, a first pin positioned adjacent the end of the cross connecting member, the pin inserted in an opening in the body, the body being provided with a cavity for receiving a spinal rod, a lever pivotally mounted to the body, a set screw mounted in a through hole in the lever that is positioned proximate to the cross connecting member so that the set screw bears against the cross connecting member when the set screw is tightened, wherein at least a portion of the lever defines a portion of the cavity. The body is rotatably mounted over the cross connecting member to rotate around the axial direction in which the cross connecting member extends. Other embodiments incorporate this body at a second end of the cross connecting member, or any of the other bodies previously described.